Universal compensating tension device

ABSTRACT

A device for maintaining constant tension in a moving strand of material comprising an arm moveable in response to changes in yarn tension between the device and the consuming utility, which movement is mechanically translated to alter the retarding force on the yarn which is exerted by a tension disc or wheel about which the yarn passes.

United" States Patent John B. Lawson Barrington, R.1. 777,352

Nov. 20, 1968 Apr. 20, 1971 Lawson-Hemphill, lnc. Central Falls, R.I.

Inventor Appl. No. Filed Patented Assignee UNIVERSAL COMPENSATING TENSION DEVICE References Cited UNITED STATES PATENTS 2/1905 Allen 242/150 l/1916 Huffman et al. 242/150 8/1927 Grout 242/156.2 11/1940 Kent 242/153X 12/1943 Buote 242/155UX 5/1951 l-leizer 242/150 6/1953 Heizer 242/155 8/1955 Wentz 242/155 9/1964 Lindsey 242/150 9/1965 Lindsey 242/150 Primary Examiner-Stanley N. Gilreath Att0rney-Paul and Paul ABSCT: A device for maintaining constant tension in a moving strand of material comprising an arm moveable in response to changes in yarn tension between the device and the consuming utility, which movement is mechanically translated to alter the retarding force on the yarn which is exerted by a tension disc or wheel about which the yarn passes.

Patented April 20, 1971 4 sheets -sheet 1 INVENTOR.

John B. Lawson ATTORNEYS.

Pfitented' April 20, 1971 4 Sheets-Sheet 2 INVENTOR. John B. Lawson WWW ATTORNEYS.

Patented 1 April 20, 1971 4 Sheets-Sheet 5 INVENTOR. John B. Lqwson W Y M ATTORNEYS.

lUhlllVlEllKSAlL CUll/lllPENSATllNG TlEhlSllUN lD lEVlltClE SUMMARY The purpose of this invention is to provide a tension device for yarn and other strands of material which is capable of maintaining tension in the yarn or strand at a preselected value as the yarn passes from a source to a consuming utility.

The devices of the present invention utilize mechanical compensating systems which are etTective to maintain uniform tension between the device and the consuming utility over a broad range of input tension values, i.e., tension variations which occur in the yarn or strand between the source and the device.

The device of the present invention is designed to be convertible to function with several different interchangeable sub assemblies, each of which is designed for particular groups of yarn types and take up machine requirements.

The necessity of maintaining uniform tension is recognized in many different textile processing applications. These include uses with knitting and weaving machinery, winding machines, twisting and spinning frames and so on.

In the past, many different devices have been designed to provide compensating tension for specific textile applications. Examples of such devices are shown in Heizer Pats. 2, 554, 493 and 2,661,913; Warwick Pat. 2,597,044 and Lawson Pat. 3,16l ,032. All of the mechanism shown in these patents are somewhat awkward and all are limited to specific yarn characteristics and specific delivery conditions.

Accordingly, the primary object of this invention is to provide a compensating tension device which is virtually universally adaptable to a variety of yarn conditions and machine requirements.

Another object of the invention is to provide a universal compensating tension device which is adaptable to the requirements of widely varying processing conditions by the interchange of simple and inexpensive components.

Other objects are to produce a tension device having a simple and compact design which is closed so that the mechanism thereof will not be impaired by lint, dust and other common mill air pollutants.

it is, furthermore, another purpose to provide a universal compensating tension device having readily interchangeable parts including springs, tension arm and tension wheels or discs.

It is also an object of the invention to provide a device of this type wherein the tension elements can be interchanged to provide either direct or indirect action.

These and other objects and advantages of the present invention will be clear from the following detailed description of preferred embodiments, and from the drawings wherein:

FlG. l is a view in perspective of a preferred embodiment of this invention.

H6. 2 is an enlarged sectional view taken in the direction of the arrows Il-ll of HG. H.

H6. 3 is an enlarged fragmentary exploded view of the device shown in lFlG. ll.

FIG. 3A is a fragmentary view in perspective of a modified form of clutch plate for the clock spring drum and of the key used in connection therewith.

FIG. 4 is a sectional view taken in the direction of the arrows lV-lV of HO. 2.

FIG. 5 is a fragmentary view in side elevation of a modification of the device of lFlGS. 14.

FIG. 6 is an enlarged fragmentary view in perspective of the the modification shown in H6. 5.

FIG. 7 is an enlarged section in plan taken in the direction of the arrows VlI-Vlll of H6. 5.

H6. 5 is a g fragmentary view in section showing another tension disc assembly.

The device 24) has a housing comprising front and rear sections 21, 22 which are held together by screws 23 of which only one is shown. An L-shaped mounting bracket 24 is secured to portion 22 by a nut 25 threaded about a hollow stud 2b and to any suitable surface S by means of a screw 27.

Yarn Y from a source not shown passes through an eyelet 25 disposed in the upper horizontal end of an S-shaped bracket 29 affixed to housing section 21 by a screw 30. From this point yarn Y passes between a pair of tension discs 31, 32 to an eyelet 33 afiixed to a lateral tab 34 of a yarn tension arm 35.

Arm 35 is attached by screw 36 to a rock shaft 37 for pivotal movement. It will be understood that variations in yarn tension between the device 20 and the ultimate utility which takes up the yarn will cause corresponding angular movement of arm 35. The purpose of the device is to translate these movements into corrective adjustments of the discs 31, 32 pursuant to which the drag exerted on the yarn thereby is varied by the amount needed to compensate for changes in tension. The mechanism for accomplishing this objective will 7 now be described.

Rock shaft 37 has a reduced end 38 which is pivotally mounted in a bearing 39 inserted in a hole in bracket 29. At its other end shaft 37 reduces to a ball 40 which is supported for rotative movement within the bore of a stud 41 which extends inwardly through rear housing section 22.

Stud 411 is supported by an annular boss 22a at the back of housing 22 and is retained against axial movement by lock ring 41a and spring washer 41b.

The device is intended to apply constant preselected tension to the yarn Y and it is thus necessary to apply selected torque to the arm 35. For this purpose, the inner end of shaft 37 has a slot 42 which receives the inner end 43 of a clock spring 44. The other end 45 of the spring 4-4 is hooked about a stud 46 extending from the back 47a of a spring drum 47.

Drum 47 is mounted coaxially of shaft 37 upon stud 41. Drum 47 can be turned relative to shaft 37 to wind and unwind spring 44 and thereby vary the torque on shaft 37. In order to ensure accurate adjustment of the torque exerted on arm 35 (and thus the tension exerted upon the yarn by the latter) the rim of drum 47 may be affixed with calibrated markings 43, 49. It will be understood that the force exerted upon the yarn by arm 35 will be proportionate to the force exerted by the spring 44. It will also be observed that the spring will normally urge the arm 44 up which is, of course, opposite the downward pull exerted thereon by yarn Y.

Drum 47 is maintained in a desired angular position by means of detent tabs 50,51 which engage the milled rim 52 of the drum. These tabs are inwardly offset extensions of a clutch plate 53 which is held between the rear of drum 47 and housing 22 in a cavity created by the boss 22a. The tabs 50, 51 are normally urged upward in a locking position by a spring 5311. The force of the spring can be overcome simply by pushing down on the top portion 53a of the clutch 53 whereupon the drum 47 can be turned to a new calibrated setting. When such manual pressure is removed, spring 53b will urge the tabs 50, 51 into locking position to maintain the desired setting.

An alternate clutch 1122 for locking spring drum S2 is d shown in FIG. 3A. This clutch requires a special key 15 to depress the clutch. Key 15 has two lugs 16 on a shank 17 which depress clutch 22 when the key is inserted into an appropriate hole 22b in the back housing half 22. Thus, key 15 is turned so that one of the lugs 16 pushes against the flat top 122a of clutch 122 thereby moving the same downwardly to release the spring drum 52 as previously described.

Tension discs 31, 32 are of conventional cup-shape having flat opposing surfaces between which the yarn is squeezed to apply a drag. The amount of drag varies in proportion to the force pressing the discs together. This compressive force is varied in compensating response to movements of the arm 35 as follows.

The discs 31l, 32 are freely rotatably mounted on a brake shaft 54 the opposing ends of which are respectively supported by and axially movable in hollow stud 26 and a bearing 55 at opposite sides of the housing 20.

Between the disc 31 and the side of the housing section 21 there is a thrust plate 56 backed by a felt pad 57. The discs themselves ride upon a shouldered bushing 53 which is slidable along shaft 54. The outside of the assembly comprises a knob 59 which screws on the threaded end of shaft 54. The inner face of the knob 59 bears against felt and metal washers 60, 61 which in turn bear upon a metal arc-shaped leaf spring 62, the rounded ends of which resiliently and uniformly press against the outer face of disc 32, thus urging the discs 31, 32 against each other.

From the foregoing, it will be apparent that the compressive force on discs 31, 32 will be decreased if shaft 54 moves to the front (to the right in FIG. 2). Conversely, such compressive force will increase upon movement of shaft 54 in the other direction.

The axial movement of shaft 54 is controlled by arm 35 so that for every movement of the arm in response to a tension change in Yarn Y the shaft 54 is simultaneously moved by a proportionate amount to adjust the compressive force on discs 31, 32 by the amount needed to compensate for the tension change in Yam Y. In this manner the tension on Yarn Y is maintained at a constant value which is selected by adjusting the wind ofclock spring 44 by turning drum 47.

In the embodiment of FIGS. 1-4, the linkage used is direct action, as will now be described.

In more detail, as best shown in FIGS. 3 and 4, rock shaft 37 comprises a front, thick portion 37a and a thinner rear portion 3711, the respective axes of which are parallel but nonconcentric. Portion 37a turns in a hole in casing wall 21 and, as it turns, the axis of portion 37b moves around the axis of portion 37a. A circular ball bearing 63 is mounted on portion 37b and thus assumes an eccentric relation to portion 37a. Each movement of arm 35 turns shaft 37 and causes a simultaneous and proportional movement of eccentrically mounted bearing 63.

To transmit the motion of bearing 63, a coupling 64 is arranged in vertical position to ride or follow the rim of the bearing. Coupling 64 moves up and down in response to turning movement of bearing 63 and in so doing causes a bellcrank 65 to rock about its pivot 66.

Thus, as best shown in FIG. 3, the upper leg 65a of the crank rests on a shoulder 67 of coupling 64. A pin 68 protruding through hole 69 in crank leg 65a and another pin 70 protruding through a hole in the bottom of casing 21 serve to maintain coupling 64 in the desired vertical position and in engagement with crank 65.

The lower end of the crank is bifurcated to produce legs 65b, 650 which straddle shaft 54. The latter is connected to the legs 65b, 65c by a pin 71 which also retains a vertical key 72 which, in conjunction with a keyway formed by walls 73, 74 at the bottom of the casing, prevent rotation of the shaft 54. A light spring 75 is disposed about shaft 54 so that its rear end bears upon hollow bolt 26 and its front exerts pressure against key 72 thus tending to urge the discs 31, 32 away from each other.

Through the foregoing linkage, upward movement of tension arm 35 (in response to decreased tension in the yarn) rotates shaft 37 counterclockwise and thus causes the eccentrically mounted bearing 63 to assume a raised position. This, in turn, raises coupling 64 to effect a clockwise movement of crank 65 about its pivot 66 whereby shaft 54 is moved inwardly to apply increased braking force to the discs 31, 32 to compensate for the decreased tension.

Conversely, if tension arm 35 moves down in response to increased tension on the yarn the linkage causes shaft 54 to move outwardly, whereby the force pressing discs 31, 32 is reduced to compensate for the increased tension.

With respect to the dynamics of the system, it will be noted that the operating level of tension arm 35 is desirably at right angles to the yarn Y as it exits from eyelet 33, as shown in FIG. 1. This position may be achieved by appropriate adjustment of knob 59 and it will be understood, of course, that the setting of this knob will vary according to the physical characteristics of the yarn and the tension imposed by spring 44.

When the system is set up for operation in the foregoing manner, the force exerted on the yarn by the discs creates a drag on the yarn reeved between them. The yarn will thus pull arm 35 down against the reaction of clock spring 44 until the discs are opened sufficiently (through movement of shaft 54) to permit the thread to flow at a tension which is nearly equal to the reaction force of spring 44. Actually, the tension on the thread Y will be equal to the reaction of the clock spring 44, less a small increment used to effect the squeezing of the thread Y by the tension discs 31, 32. It should further be noted that this system will function as the input tension varies to maintain a uniform output tension up to the point where the input thread tension is nearly equal to the output tension at which point the tension discs will be fully opened and all the regulatory powers on thread flow are lost.

The embodiment shown in FIGS. 57 illustrates the interchangeable nature of the yarn tensioning device of this invention. In this embodiment, a friction wheel is used in lieu of discs 31, 32 and the arm thereof has a thread wheel 128 instead of eyelet 33.

The thread wheel 100 comprises molded discs or shells 131, 132 which are formed with radially extending ridges 133 and intervening recesses 134 on their inner (facing) surfaces. The shells 131, 132 also have a series of circumferentially spaced depressions 135 on their outer surfaces which form inwardly projecting knobs 136 on their inner surfaces. Between spaces 135 are projections 137 which form depressions 138 on the inner surfaces.

When the shells 131, 132 are placed together, the opposing alternate ridges 133 and recesses 134 interlock, as do the knobs 136 and depressions 138. Thus a yarn reeved between the shells must weave back and forth around the spokes 133 creating in the yarn many frictional contacts. Radial movement of the yarn is not possible inwardly beyond the barrier presented by the knobs 136 and depressions 138. The yarn may be reeved about the friction wheel 100 several times in order to prevent slippage and thus the yarn will move only when the wheel turns.

The shells 131, 132 are clamped between a threaded hub 139 and a nut 140 supported on an axially moveable pressure shaft 154. Friction wheel assembly 100 is braked against rotation to effect a resistance to thread flow by the squeeze of hub 139 against thrust washer 141 via adjusting knob 159, felt washer and spacer 161 in relation to axial movements of the pressure shaft 154. The braking force exerted on friction wheel 100 is thus related to movements of tension arm 135 in the same manner as the squeezing force on discs 3l32 of the first embodiment is related to movements of arm 35 of such embodiment. Therefore, the indirect technique of holding the yarn using friction wheel 100 is regulated by the tension arm to effect a controlled output tension in the same manner as previously described for the tension discs 3132. It should be noted that the friction wheel assembly 100 may be disassembled easily by unscrewing nut 140 from hub 139 to clean any filaments of yarn or lint that might have become trapped between the shells 131, 132.

The device shown in FIGS. 5-7 uses an indirect linkage system for moving pressure shaft 154, whereas the first system is direct. Nevertheless, the action of the arm 135, eccentric bearing 163 and shaft 154 is the same as previously described for the same components forming part of the embodiment of FIGS. 1-4. The indirect linkage system is best shown in FIG. 6 wherein a compression connector 164 is shown disposed under ball bearing 163. Connector 164 is guided on an extension which projects through a hole in the front housing half 21 and a similar extension 163 which projects through a hole 169 in the rocking crank 165. Movements of the tension arm 135 are transmitted to the rocking crank 165 through the connector 164.

The rocking crank 165 is of the same design as that used with the direct action linkage shown in FIG. 3, but acts by indirect action upon the pressure shaft 154, as follows. An extension link has a pair of ears 181, 182 which lock into a pair of holes in the sidewalls of crank 165. The extension link is U-shaped with a hole through which the pressure shaft H54 passes. inside link 150 a key 172 is pinned to the pressure shaft 154 by a short pin 171. The key 172 prevents rotation of the pressure shaft 154i in a manner previously described. A spring 175 slides over the pressure shaft 154 between the key 170 and the thrust bushing Mil to urge the pressure shaft inwardly to impose a braking action upon the wheel Mill and thereby to effect a drag on the yarn in a manner previously described.

in this embodiment, when the tension arm 135 moves up, the ball bearing 163 moves vertically away from the connector 1M whereupon the latter rises under the influence of spring 1'75 which causes clockwise rotation of the crank 165. This allows shaft 153 to move inwardly to effect braking pressure on the friction wheel 1%, which pressure is a function of the force of spring 1175.

Conversely, if the tension arm moves or is pulled down, the reverse movements of the linkage takes place and the extension link rsu pulls against the key 170 on shaft 154 to positively release the pressure on the wheel lltltl whereby the wheel will be more freely rotatable to relieve a compensating amount of drag on the yarn.

In the indirect system which has been described, the wheel 1M1 (or discs 31, 32 when used) act as a yarn holding element and the maximum holding force which can be exerted on the yarn is a function of the spring 175. in this embodiment, it should be noted that the tension arm 135 will not be restricted from moving upward when the wheel llllll is braked (or the discs 31, 32 are closed). Thus, the indirect linkage holds the yarn taut even after the yarn stops flowing to the utility.

The arm 135 is suitable for a stop motion contact as shown in H6. 5. Thus, a contact 1% is fastened to the side of the front housing half between a pair of insulating spacers. The contact 1% is shaped so that if the tension arm 135 should be released-as with a broken end of yarnthe arm would rise until the tail of the tension arm engaged the contact 1%, closing a circuit through the unit to a wire 191 connected to a system for stopping the associated machines, in a manner well known in the textile industry.

Furthermore, using the indirect system, turning adjusting knob 1159 sets the braking point of the yarn elements through the linkage, and effectively positions the operating level of the tension arm 135.

it will be understood that the indirect linkage system and/or the stop motion mechanism just described can be used interchangeably in connection with the device shown in F 165. 1-4.

A further embodiment of a tension disc which may be used with the devices described is shown in FIG. 5. in this embodiment, the tension discs 23H, 232 are fabricated such as by molding with a hollow annular hub 29% forming a chamber 291 in which a rotating element such as a ball bearing 292 may be set on the pressure shaft 254. The ball bearing 292 has a sheave 253 on its outer race which provides a drag-free surface about which the yarn may travel when the discs 231, 232 are open. Use of the ball bearing arrangement shown in F161. 5 is not recommended, however, where a substantial amount of lint is encountered and may be replaced by a low friction sheave.

In the foregoing, there have been described a basic yarn tension unit together with a number of subassemblies which can be used interchangeably in the unit. These subassemblies include different types of devices for imposing drag on the yarn including the discs 31, 32 and 231, 232 and the friction wheel lltllll, direct and indirect linkage systems and the yarn tension arms 35 and 135. Maximum performance and efliciency can be achieved by selecting different subassemblies according to the variables of the type of yarn to be tensioned and the nature of the equipment involved, as per the following examples:

EXAMPLE I One wishes to tension a filament yarn to a knitting machine at between 3 & 8 grams.

The important characteristics of this problem are:

a. A stop motion is required.

b. There is no major lint problem.

c. Easy knit passage is desired.

The combinations used would be:

a. indirect action linkage to allow for a stop motion and to allow for easy knot passage with discs.

b. Disc tensions for simplicity and to minimize wear.

c. A light clock spring to reduce sensitivity in tension selections.

d. A wheel tension arm 135 since there is no lint problem to reduce a frictional loss at this guide point.

EXAMPLE 2 EXAMPLE 3 To tension a spandex at 200 grams to a spinning frame.

important characteristics:

a. High lint condition.

b. High friction.

c. Steady thread flow.

Selected Combinations:

a. Because of the high lint discs 31, 32 are used.

b. Because of the high lint a guide 33 is used on the tension arm 35.

c. Heavy clock spring.

d. Direct action linkage.

EXAMPLE 4 To tension a knobby yarn at 30 grams to beam.

Important Characteristics:

a. Minimum lint.

b. Knob forms on yarn.

c. Stop motion desirable.

Selection of Elements:

a. Friction wheel to allow the smooth flow of knobs.

b. indirect action linkage for the stop motion.

c. Medium clock spring.

d. Thread guide 33 on the tension arm 35 to minimize the chance of a thread jumping off a wheel.

EXAMPLE 5 To tension a knobby yarn at 30 grams to a cone wider.

Important characteristics:

a. lumpy yarn flow because of the fast traverse.

b. Knobs form on yarn.

c. No stop motion needed.

d. Minimum lint.

Selected elements:

a. Medium clock spring.

b. Discs 311, 32 or 231, 232 are used as the friction wheel would not respond well to the fast variation in yarn flow.

c. Indirect action linkage to help knob flow through the discs.

d. A wheel 1% on the tension arm 135.

EXAMPLE 6 To tension a spun yarn to a filling needle on a narrow shuttleless loom at 5 grams.

Important features:

a. High lint.

b. Intermittent flow.

c. Stop motion needed.

Selection of elements:

a. Disc tension 31, 32 because oflint.

b. Indirect action linkage for stop motion.

c. Guide 38 on tension arm 35 because of lint and to eliminate the danger of a yarn fall offa wheel.

d. Low value clock spring.

In general, selection of elements may be governed by the following characteristics. Discs are good on filament yarns and are used when the flow of yarn varies rapidly. The friction wheel is less abusive to a yarn and is used whenever the yarn flow is steady or the yarn is elastic enough to absorb any variations in the yarn travel rate. Friction wheels are selected in high friction situations or when the surface characteristic of the yarn is irregular. Friction wheels are not suitable for strong lint conditions as they back up. Thread guides on the tension arm are used when there is a high lint condition or when there is danger of loosing the yarn off a pulley. In all other applications a wheel is preferred, The direct action linkage is used where high tensions are encountered, and in general the indirect action linkage is used when stop motion contacts are desired, and in all low tension applications with discs since this arrangement allows for an opening of the discs, as when a knot passes, without forcing a movement in the tension arm. The clock spring selection is of course dictated by the degree of tension required, but the softest setting compatible with the requirements should be used to minimize the sensitivity to adjustments.

lclaim:

1. In a tension device for selectively applying tension to yarn, said device having a rock shaft, a rockable arm secured at one end to the rock shaft and having a yarn guide disposed at its distal end,

A. Means for imparting a selected tension yarn including:

a. a spiral spring for biasing the rockable arm to impose the desired selected tension on the yarn,

b. means for winding the spiral spring to selected spring tension,

c. a drum containing the spiral spring having a succession of peripheral teeth disposed thereon,

d. a detent for engaging the teeth to prevent rotary movement of the drum,

e. a clutch plate for disengaging the detent from the drum teeth and f. resilient means urging the detent into engagement with the drum teeth; and

B. Yarn braking means for exerting a drag on the yarn as it passes to the yarn guide including:

a. an eccentric mounted on the rock shaft and responsive to rocking movement of the arm,

b. a brake shaft on which the yarn braking means is mounted, said brake shaft being movable axially to increase or decrease the drag on the yarn,

c. resilient means adapted to urge the brake shaft in a selected axial direction and d. transmission means disposed between the eccentric and the brake shaft in response to rocking movement of the arm.

2. The yarn tension device of claim I wherein the clutch plate and detent are integrally formed.

3. The yarn tension device of claim 2 further including a. an aperture in the clutch plate and b. key means for engaging the aperture in the clutch plate for disengaging the detent from the drum teeth. 

1. In a tension device for selectively applying tension to yarn, said device having a rock shaft, a rockable arm secured at one end to the rock shaft and having a yarn guide disposed at its distal end, A. Means for imparting a selected tension yarn including: a. a spiral spring for biasing the rockable arm to impose the desired selected tension on the yarn, b. means for winding the spiral spring to selected spring tension, c. a drum containing the spiral spring having a succession of peripheral teeth disposed thereon, d. a detent for engaging the teeth to prevent rotary movement of the drum, e. a clutch plate for disengaging the detent from the drum teeth and f. resilient means urging the detent into engagement with the drum teeth; and B. Yarn braking means for exerting a drag on the yarn as it passes to the yarn guide including: a. an eccentric mounted on the rock shaft and responsive to rocking movement of the arm, b. a brake shaft on which the yarn braking means is mounted, said brake shaft being movable axially to increase or decrease the drag on the yarn, c. resilient means adapted to urge the brake shaft in a selected axial direction and d. transmission means disposed between the eccentric and the brake shaft in response to rocking movement of the arm.
 2. The yarn tension device of claim 1 wherein the clutch plate and detent are integrally formed.
 3. The yarn tension device of claim 2 further including a. an aperture in the clutch plate and b. key means for engaging the aperture in the clutch plate for disengaging the detent from the drum teeth. 